Package management in Ubuntu Server

Search for existing packages: apt-cache search openjdk
Install: apt-get install openjdk-7-jdk or dpkg -i <file.deb>
List installed packages: dpkg -l | grep <package-name> or dpkg --get-selections | grep <package-name>
Remove(uninstall): apt-get purge openjdk-7-jdk or apt-get remove openjdk-7-jdk or use purge instead, see apt-get help. Or use dpkg:
```
dpkg -r <package_name>
dpkg -P <package_name>
```
Hold a package(not upgrade anymore): aptitude hold <package-name> Release the holding of a package: aptitude unhold <package-name> Use for package name auto-completion.